Since marine deposits well preserve information on the environmental change on Earth, they are used as data for paleoenvironmental research and include mineral resources at sea (gas, gas hydrate, manganese nodule, phosphate rock, marine sand, or the like), such that they have been in the limelight as an energy source.
Further, the marine deposits have been used as research data for marine pollution or pollutants originated from a land.
As described above, since the marine deposits can be used as various purposes, there is a need to collect marine deposits. To this end, various types of apparatuses for collecting marine deposits have been proposed.
As these apparatuses for collecting marine deposits, there are a grab, a dredge, a piston corer, a gravity corer, a multi corer (see Korean Patent Application No. 10-20005-0132098, or the like), or the like.
The grab is mainly used at the coast, which is used for dredging polluted marine deposits and the dredge for maintaining waterways. However, the grab has a problem in entirely disturbing the collected deposits (mixing or distorting the marine deposits, not keeping the depositional structures).
Further, the dredge is a method for collecting marine deposits while a ship is moving. The dredge is mainly used for collecting rocks such as manganese nodule and solidified phosphate rock included in the marine deposits.
Since the dredge entirely disturbs the marine deposits collected and should move over the wide area, there is a problem in that it cannot accurately know a sample collecting position.
The piston corer apparatus has a structure having a piston corer in which a piston body composed of a plastic material serving as a piston is inserted into an external body serving as a cylinder body. In detail, the piston corer has a structure in which the piston corer instantly falls free while the wound cable is untied when a trigger weight installed at the side bottom portion of the piston corer and serving as a weight first reaches the seafloor and is stuck in a deep part of the sea bottom, thereby collecting the marine deposits.
That is, when the trigger weight does not reach the seafloor, the piston corer slowly falls along the trigger weight from the side top point of the trigger weight, but when the trigger weight reaches the seafloor, the piston corer rapidly falls while a rope connected and wound on the piston corer is untied, such that it is struck in the deep part of the sea bottom.
When the piston corer is stuck in the sea bottom, since the piston body moves to the upper portion of the external body, the marine deposits are smoothly filled in the external body.
When the piston corer is stuck in the sea bottom, a considerable impact is applied to the seafloor. As a result, a method of using the piston corer disturbs the surface part of the marine deposits but is deeply stuck in the sea bottom (up to the deep part) and does not disturb marine deposits at a deep part of the sea bottom, thereby making it possible to effectively and stably secure the marine deposits at the deep part.
A length of the piston corer is manufactured in consideration of a length of a ship or a height of a winch. Generally, the piston corer is manufactured to have a length of about 3 m to 15 m.
The gravity corer apparatus has a structure having a gravity corer in which a plastic pipe serving as a piston is inserted into an iron pipe serving as a cylinder body. The gravity corer apparatus is stuck in the sea bottom by its own weight and a free fall force, thereby collecting the marine deposits.
When the gravity corer reaches the seafloor, a considerable impact is applied to the sea bottom, such that a disturbance phenomenon occurs at the top portion of the marine deposits.
The length of the gravity corer is similar to that of the piston corer; however, the weight of the gravity corer is much heavier than that of the piston corer.
The box corer apparatus has a structure having a box corer composed of a metal material having a collecting body positioned at the middle thereof, while the top and bottom portions thereof are not closed. When the frame reaches the seafloor, the collecting body moves towards the marine deposits, the lower stopper having the shovel shape descends, thereby collecting the marine deposits.
The box corer can collect the marine deposits at a depth of about 1 m without disturbing the surface part of marine deposits.
However, the box corer has a problem in that it is difficult to attach and detach the collection body and it takes a long time to attach and detach the collecting body.
The multi corer apparatus has a structure in which approximately 6 to 8 collecting bodies having a pipe shape and composed of a plastic material are installed in a frame. When the frame of the multi corer reaches the seafloor, it is triggered to move the collecting body towards the marine deposits, thereby collecting the marine deposits.
The multi corer can collect the marine deposits at about 50 cm from the seafloor without causing the disturbance of the marine deposits at the upper portion of the seafloor.
The multi corer needs less time to attach and detach the collecting body as compared to the box corer, but has a disadvantage in that the volume of the apparatus is large.
Meanwhile, a method for collecting marine deposits is optionally selected depending on the purpose. In some cases, several methods may be used together at the same position.
The collecting time of the marine deposits depends on the depth of water of an area to be probed. In the case of the deep sea, the collecting time can take as long as several hours to collect the marine deposits.
The piston corer or the gravity corer is used to collect the marine deposits for research of paleoenvironment or mineral resources at the sea. The primary purpose thereof is to obtain the marine deposits at a possible deep part within the range where the conditions of the ship is permitted.
Further, since the deposits at a depth of 50 cm from the sea bottom are data through which a recent deposited environment can be appreciated, the multi corer or the box corer has been used to collect the marine deposits in the state in which the marine deposits are not disturbed.
There are cases in which the marine deposits at the surface part of the seafloor are collected in the same position and the marine deposits at the deep part of the sea bottom are secured.
To this end, the deposits were collected up to the deep part of the sea bottom through the piston corer or the gravity corer and were collected in the state in which the marine deposits of the surface part of the sea bottom are not disturbed.
That is, the collecting work of the marine deposits was performed twice at the same position.
The working method increases costs consumed to probe the marine deposits and has low accuracy of probe.
Even though the collecting apparatus is introduced into the sea bottom from the same position on the sea, the case where each collecting apparatus is not arrived at the same sea bottom due to the influence of sea current, or the like frequently occurs, which degrades the accuracy of collecting the marine deposits.